How to build:
– First, enjoy the beer, thats a mandatory step. 😉
– Remove the top cover of the can. In a way, that you keep the outer folded ring.
-Drill a hole in the bottom center to insert the BNC/SMA socket.
– Solder the welding rod to the BNC/SMA center contact.
– Measure the length of the rod including the center contact and cut the overall length to 490mm.
– Insert the socket through the bottom hole and fix with the nut.
– Cover the top opening with some non-conductive material. I used some EPS foam.
– That´s all.

I made a extension pipe with a BNC socket on one end and some tripod adapter on the other. This way I can raise the antenna up to 3m on the tripod.
The antenna connects with a 5m BNC cable to the transmitter.

I have tested the antenna during my 11km flight with excellent results.

A fellow pilot uses a second antenna with 433MHz 3DR radio modes to control his APM2.5 plane. He was 3km out already then chickened.

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Note, a different size beer can may require a different length of the welding rod.